1. Field of the Invention
The present invention relates generally to communication systems, and more particularly, the present invention relates to a scheduler and related method for efficiently granting polls to upstream and/or sidestream traffic and sending downstream frames.
2. Description of the Related Art
Scheduling is essential in providing quality of service (QoS) in data networks where multiple users share common resources. This is especially true in the context of wireless links. That is, the time-varying nature of wireless links presents great challenges in the design of scheduling policy in wireless data services because of the scarcity of radio resource and the time-varying nature of radio quality. Currently, most scheduling policies are dependent on the queue length or arrival rate or time stamps present in a transmitted medium access control (MAC) frame and do not consider the channel capacity. This would suffice if the channel capacity to all users were constant as is the case in wire-line systems. However, in the context of wireless networks, a drawback of these schemes is that they always result in an under-utilization of the wireless resources by not accounting for the channel capacity (i.e., the channel condition and continuously varying transmission rate).
Currently, the 802.11 MAC offers a simplified model, referred to as a “best-effort” model. In the simplified scheme, all frames receive the same level of service with no distinction for frames from different applications. In accordance with the model, an attempt is made to forward frames as soon as possible, but makes no quantitative commitments about the quality of service (QoS) provisioning. But with the advent of 802.11e, which is a quality of service MAC, a scheduler is needed to guarantee the QoS requirements for different streams.
Accordingly, there is a need for a scheduling policy that can be incorporated on top of the IEEE 802.11e/D4.0. draft standard enabling an QoS access point (QAP) to take into account the QoS requirements of the stream and schedule appropriately.